The news agency says 56 workers were down the shaft when the flooding occurred Thursday afternoon at the privately owned Anzhishun Coal Mine in Jixi City. Xinhua cites the public security bureau of Jixi as saying 33 of the workers were lifted to the ground.

Xinhua says rescuers are installing pumps to drain the flood shaft. The mine’s owner has been placed in police custody.

The news agency gave no details on what caused the flood.

China has some of the world’s deadliest mines, but they are getting safer with stricter work safety enforcement.